Thousands
of sports fans and implosion enthusiasts recently braved freezing
pre-dawn temperatures along the Ohio River to watch D.H. Griffin
of Franklin, Tennessee successfully fell Riverfront Stadium
in Cincinnati, Ohio.
To prepare
for the implosion, blaster Steve Pettigrew and his team drilled
more than 2,500 holes in concrete supports throughout the
1,600-foot long structure. The holes were then loaded with
approximately 1,800 pounds of 40% nitroglycerin-based explosives.
Linear shaped RDX charges were also attached to the steel
supports of the upper grandstand to ensure an inward, smooth-flowing
collapse towards the playing field.
From a
liability standpoint, the implosion was the most difficult
stadium blast ever attempted. Standing less than 24 feet to
the east were hundreds of floor-to-ceiling height windows
along the perimeter of the new Great American Ballpark. To
the west sat the Charles A. Roebling suspension bridge, Cincinnati's
most prominent historic landmark dating back to the Civil-War
era. After the event it was determined that not a single window
was broken in the new stadium, and both adjacent structures
were left completely unharmed.
With previous
blasts such as Fulton County Stadium and Exhibition Stadium
to their credit, the Riverfront Stadium project solidified
D.H. Griffin's record as the only blast team in America to
successfully raze full-sized sports stadiums without complications.
Dykon
president Jim Redyke devised a blast plan to drop the 70-year-old,
180-foot by 130-foot steel truss roof straight down onto the
building's pre-stressed concrete floor using 14 pounds of
RDX linear shaped explosive charges on a single delay. Redyke's
plan also called for meticulous preparatory operations such
as saw-cutting a three-foot wide gap around the perimeter
of the structure's basement slab (to help mitigate the transmission
of ground vibration) and covering the closest adjacent windows
and doorways with protective plywood panels and geotextile
fabric. These activities were completed on a strict timeline
under the direct supervision of Pitsch Vice President, Gary
Pitsch.
As an
added measure of security, project officials contracted Protec
Documentation Services, Hainesport, New Jersey, to forecast
and calculate ground vibration and airblast levels prior to
the demolition. The team also performed detailed pre-blast
inspections of various structures surrounding the site, including
the four-star Grand Plaza Hotel and the existing auditorium
lobby located ten feet from the roof's closest point of impact.
The blast
was scheduled for 3:00pm on a Saturday afternoon so as not
to interfere with business activities or nearby church services.
Thousands of local residents who had lined up along nearby
rooftops and the banks of the Grand River then watched and
cheered as a single sharp explosion brought the giant steel
trusses down within a majestic swirl of dust, directly onto
their intended zone. Following the blast, it was confirmed
that all adjacent buildings remained unharmed, and vibration
levels recorded at various locations were slightly less than
predicted.
